Over time, carbon decays in predictable ways. And with the help of radiocarbon dating, researchers can use that decay as a kind of clock that allows them to peer into the past and determine absolute dates for everything from wood to food, pollen, poop, and even dead animals and humans. While plants are alive, they take in carbon through photosynthesis.
Humans and other animals ingest the carbon through plant-based foods or by eating other animals that eat plants. Carbon is made up of three isotopes. The most abundant, carbon, remains stable in the atmosphere.
On the other hand, carbon is radioactive and decays into nitrogen over time. Every 5, years, the radioactivity of carbon decays by half. That half-life is critical to radiocarbon dating. The less radioactivity a carbon isotope emits, the older it is.
But the amount of carbon in tree rings with known ages can help scientists correct for those fluctuations. To date an object, researchers use mass spectrometers or other instruments to determine the ratio of carbon and carbon The result is then calibrated and presented along with a margin of error.
Discover other archaeological methods used to date sites. Chemist Willard Libby first realized that carbon could act like a clock in the s. He won the Nobel Prize in Chemistry for coming up with the method. The method has limitations: Samples can be contaminated by other carbon-containing materials, like the soil that surrounds some bones or labels that contain animal-based glue. Age is also a problem: Samples that are older than about 40, years are extremely difficult to date due to tiny levels of carbon Calibration presents another challenge.
With the dawn of the Industrial Age, humans began emitting much more carbon dioxide, diluting the amount of radiocarbon in the atmosphere.
Radiocarbon dating and archaeology
Nuclear testing affects radiocarbon levels, too, and dramatically increased carbon levels starting in the s. See how radiocarbon dating helped researchers determine when this ship sank. All rights reserved. Counting carbon While plants are alive, they take in carbon through photosynthesis.
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